Treatment of hydrocarbons



Patented Apr 5, 1938 PATENT- OFFICE TBEATllIENTOI HYDROOABBONS Vladimir Ipatiefl and Hermanllnca. Chicago,

Universal Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing. Application May 1, 1937,

Serial No. 149,164

6 Claims. (CL 260-169) This invention relates particularly to the treatment of paraflin hydrocarbons which are gaseous at ordinary temperatures and pressures, and particularly isobutane.

5 In a more specific sense, the invention is concerned with a novel process 'foralkylating iso-. butane with olefins which are normally gaseous to produce saturated hydrocarbons of higher molecular weight which can be utilized as constituents 10 of motor fuel for automobile and aeroplane engines.

The cracking process which is operated principally with the object of producing gasoline from heavier and less valuable petroleum fractions 15 incidentally produces considerable yields of fixed gases comprising hydrogen, methane, ethane, propane, and butanes as well asethylene, propylene, and butylenes in varying quantities and' proportions. In most instances, these gases are yields of motor fuel fractions to augment those.

primarily produced by thecracking operation. While the process is particularly applicable to 30 the utilization of the hydrocarbons in cracked gas mixtures, and particularly selected fractions produced therefrom in the stabilizers of cracking.

plants, it is also applicable to the treatment of. isobutane and propylene produced from anyother 35 source.

In one specific embodiment the present invention comprises the alkylation of isobutane with propylene at temperatures of C. or below with catalysts comprising aluminum chloride and hy- 40 drogen chloride. I

In a preferred embodiment of the invention the desired allwlation reactions are activated or socelerated by the presence of small quantities of olefins more reactive than propylene which may 45 be added continuously during a run or used to treat the catalyst prior to its use in the alkylation reactions with propylene. This point will be developed in greater detail in a later portion of the specificatiom 50 An essential feature of the present invention is the utilization of suificiently' low temperatures of treatment so that the ordinarily vigorous action of aluminum chloride in catalyzing condensation reactions among hydrocarbons is moderated and polymerization of the olefin involved. In other words, at the selected low temperatures employed .the rate of the polymerization reactions is reduced while apparently the rate of the alkylation reactions is not reduced to the same extent so that alkylation takw place in preference to polythe preferred range of conditions will necessarily involve to some extent not only simple alkylation corresponding to the addition of one or more molecules of the olefin to the isoparafiln but also some reaction of polymerization and some reactions of decomposition, so that the net result is the production of a mixture of hydrocarbons hav-' ing a considerable bollingrange but containing a major proportion of monoand di-alkylated products as will be shown in a later example.

The actual operation of the process admits of some modification depending upon the normal phase of the reacting constituents and whether batch or continuous operations are employed. In a simple type of batch operation involving substantially only the pure compounds isobutane and propylene the isobutane is cooled to a temperature of 0 C. or below in the presence of a minor percentage of anhydrous aluminum chloride and alkylation is eifected by the gradual introduction of. propylene under the surface of the liquid which may be mechanically stirred to prevent subsidence of the solid aluminum chloride particles. A small percentage of hydrogen chloride is preferably admitted along with the stream of olefin vapor, and for eifecting more rapid and complete alkylation it is best practice to add also a small percentage of a more reactive olefin such as, for example, isobutylene or normal butylenes. After a treatment is completed the aluminum chloride layer is allowed to settle, and the upper hydrocarbon layer is removed by 'decantation and subjected to'fractionation for the removal of uncombined hydrocarbons as a light overhead and the recovery of an intermediate motor fuel frac--. tion. v v

' In continuous operation'liquid isobutane containing suspended therelnthe requisite amount of aluminum chlorldeand cooled to a suitably low temperature may be pumped through a tubular treater at the entrance to which it receives the 50 necessary addition of propylene and hydrogen chloride, the desired allrylation taking place dur-i ing pasage through the treater and the fractionaticn of the products being accomplished in a submlent fractions-for. The details of con-1 tinuous process ofthis general character are more or less familiar to those skilled in oil refinery operations and any necessary addition to or modi- ,flcations of the above general procedures will be more 'or less obvious, and can be made without j departing from the general scope of the invention. The preliminary activation of the" alkylation reaction may be effected by treating the granular aluminum chloride intended for use in the reactions with either normal or isobutylenes by passing a limited amount of these compounds in liquid-phase in contact with the granular material during vigorous agitation. The pronounced'effect of this activation upon the speed of subsequent alkylation reactions with propylene is of reaction which has the efiect of energizing the less reactive propylene. It has been observed that the activating effect is gradually lost so-that in a strict sense it is not entirely catalytic. This feature of the present process is important from a practical standpoint since, when using pure propylene or at least propylene free from other olefins, the. speed of the alkylation reactions is sometimes below a practical level at the temperatures necessary to prevent polymerization. The

preliminary treatment of granular aluminum chloride with relatively highly reactive oleflns, such as isolmtylene or normal butylenes, has been observed to have a still further effect ofpractical significance, in that there is a greatly decreased tendency for the chloride particles to become very finely divided under vigorous agitation but rather to maintain their original size, which prevents the carrying ofl of the catalyst in colloidal suspension in continuous processes.

The reacting hydrocarbons required for 'the present process may be obtained from any convenient source. As a rule the best sources are the cracked gas mixtures produced in the pyrolysis of heavy oils with the primary object of producing gasoline. The technique of hydrocarbon fractionation is sufiicientiy developed at the present time so that it is commercially feasible to produce relatively pure propylene and isobutane.- A

method which may be employed to obtain propylene which is not contaminated with paraiiin hydrocarbons consists in the use of solvents which selectively abstract oleflns from the gas mixtures, which oieilns are then separately fractionated. In such a process the residual unabsorbed paraffln mixture may be employed as the source of the required isobutane. .Propylene may also be pre- 7 pared by the selective catalytic dehydrogenation of propane or propane fractions. Over the preferred low temperature conditio of operation and in the presence of an excessoi' isobutane, one molecule of propylene tends to react with its molecular equivalent of isobutane while the excess-of isobutane remains unaffected. when more propylene is used than corresponds to about one mole'of propylene to three moles of isobutane there is an increased tendency for poly-- meriration reactionsto occur in preference to alkylation reactions; m is to be expected to some .extent on account of the readiness with which propylene aloneis polymerized by alumi- .invention in exact conformity with the pm chloride. However, by maintaining the proper excess of the paraffin hydrocarbon the course of the reactions may be kept principally 'in the direction of production of alkylated prodpots of a saturatedrather thanfan oleflnicfchar acter; Inorder to balance up any disproportion" on the side of either the olefin or the paraflln, to produce products of the desired degreeof alkylation either may be added from outside sources to produce a mixture of proper proportions. It will beshown in subsequent examples that there is some production of isodecanes as well as isoheptanes, the former compounds corresponding to alkylation of isobutane by two isopropyl groups.

The process may be utilized for the direct improvement of low antiknock value gasolines by suspending aluminum chloride therein at the required low temperatures and passing a. proportioned mixture of isobutane and propylene into the suspension along with a trace of hydrogen chloride. The gasoline functions both as a solvent and a reaction medium and the alkylation products are formedand blended with the gasoline at the same time to increase its antiknock value to an extent depending upon the amount of alkylated'products formed. y

. The following examples are given as illustrative of the type of results normally obtainable by the use of the present process, although it is not given with the intention of limiting the scope of the data presented.

I Example I Granular anhydrous aluminum chloride was "placed in a reaction vessel which was cooled to pended aluminum chloride while reaction products were siphoned from the reaction vessel at a sufliciently high level to avoid removal of the catalyst particles; The charge consisted of approximately 7'7 per cent of isobutane and 23 percent of propylene, calculated on a gas basis; and a steady feed of a small amount of hydrogen chloride was maintained during the run.

3250 volumes of isobutane-propylene mixture produced 650 volumes of liquids boiling within the ordinary range of commercial gasoline or up to approximately 225 C. of the'total liquid products boiled below.220 C. and the'octane number of this gasoline fraction was 81 when tested by the motor method. Careful fractionation indicated that 42% of the total liquid productsconsisted of isoheptanes boiling between 88 and 90 C. and another 20 percent of the liquid products corresponded to isodecanes boiling -be-' tween and154 C.

. v Example II A run was made at the upperlimit of tem-j perature corresponding to the economical and practical operation of the The general procedure was the same as iriExampie I in to the relative pro r ons: the hydrocarbons reacted in the presence of chloride.

Inthis case, however, 30001volurnes oi isobutanebelow 200 C. The octane numberof the 200 0.. end point fraction was 83 by the motor method and it was noted that there was a somewhat higher percentage of material boiling below the 50% point in the distillation test. In comparison with the first case, a careful fractionation showed that 39% of the total liquid products consisted of isoheptanes instead of 42% as in the first example. I

The foregoing specification has disclosed the character and scope of the present invention and the examples have shown its practical aspects but neither section is to be considered as unduly limiting.

This application is a I our co-pending application Serial No. 103,389,

filed September 30, 1936.

We claim as our invention:

1. A processior the production atives of isobutane which comprises subjecting said isobutane to the action of propylene in the presence of aluminum. chloride and hydrogen chloride at a-temperature of 0 C. or below.

2. A process for the tives of isobutane which comprises subjecting said isobutane to the action of propylene in the presence of aluminum chloride and hydrogen chloride at temperatures within the range of 0 C. 50 C.

continuation-in-part of I of alkyl derivproduction of alkyl deriva 3. A process for the production of alkyl derivatives of isobutane which comprises subjecting said isobutane to the action of propylene and a minor proportion of a more reactive olefln in the presence of aluminum chloride and hydrogen chloride at a temperature of 0 C. or below.

4. A process for the production of alkyl derivatives of isobutane which comprises subjecting said isobutane to the action of propylene and a minor proportion of 'a butylene in the presence of aluminum chloride and hydrogen chloride at a temperature of 0 C. or below.

5. A process for the production of alkyl derivatlves of isobutane which comprises subjecting said isobutane to the action of propylene and a minor proportion of a normal butylene in the presence of aluminum chloride and hydrogen chloride at a temperature of 0 C. or below. 6. A process for the production of alkyl derivatives of isobutane which comprises subjecting said isobutane to the action of propylene and a minor proportion of isobutylene in the presence of aluminum chloride and hydrogen chloride at-a temperature of 0 C, or below.

- VLADIMIR IPA'I'IEFF.

HERMAN PINES. 

